1. Field of the Invention
The present invention relates to prosthetics and, more particularly, to a prosthetic-limb coupling-socket adapter assembly that affords angular adjustment for the prosthetic limb, yet does not significantly increase the profile length of the interconnection between socket and knee or foot joint for amputation patients.
2. Description of the Background
There are a variety of different types of prosthetic devices for patients that have had either transfemoral (above-knee) or transtibial (below the knee) amputation. A typical transfemoral prosthetic device consists of a custom socket fitted over the residual limb, a structural component system affixed to the socket that may include a pylon and articulated replacement joints (such as a knee or ankle) depending on the patient and location of the amputation, and knee cuffs, belts or other systems to secure the device to the body. A prosthetic sock or liner is typically worn over the residual limb within the socket to cushion the area of contact, and, in some cases, realistic-looking skin is provided over the structural components for aesthetic reasons.
As shown in FIG. 1, the socket 22 receives the wearer's residual limb. The socket 22 is typically a fiberglass or other composite shell molded to conform to the user's residual limb. The socket 22 is seated on a choke adapter 24. Choke adapter 24 includes an array of branches 26 that grip the socket 22. Typically, the branches 26 are integrally and permanently molded inside the socket 22. The permanently-attached choke adapter 24 positions a screw-tightenable C-ring clamping collar 28 directly beneath the socket 22. In addition to being screw-tightenable in a clamping manner, collar 28 is internally threaded. A pyramid receptacle 40 includes an externally-threaded end that is screw-threaded into the collar 28 of choke adapter 24. The other end of pyramid receptacle 40 screw-clamps to a pyramidal link-plate 10 mounted to the knee-joint assembly for transfemoral (above-knee) patients. Alternatively, the other end of pyramid receptacle 40 screw-clamps to a pyramidal coupling on a foot assembly for transtibial (below the knee) patients. A plurality of screws may be inserted through holes 18 in the pyramidal link-plate 10 to secure it to the respective prosthetic limb components fastened there beneath (an articulating knee joint and foot are shown). The conventional pyramidal link-plate 10 and the conventional pyramid receptacle 40 are primarily based upon the “Adjustable Link” described in U.S. Pat. No. 3,659,294 to Glabiszewski, the disclosure of which is incorporated herein by reference.
Specifically, and as shown in FIG. 1, the conventional pyramidal link-plate 10 wields a frustopyramidal, four-sided boss 12 projecting from a dome-shaped, or a spherically-convex-shaped base 14, which in turn projects from a plate member 16. The plate member 16 will typically include four screw- or bolt-receiving, through-holes 18 corresponding to a standard (within the industry) four-hole pattern. The pyramid receptacle 40 fits over the four-sided boss 12, is angularly adjusted as desired, and then screw-clamps by set screws 45 onto the four-sided boss 12 to maintain the alignment. In fitting prosthetic limbs to patients, it is often necessary to modify and adjust the alignment and orientations of the various prosthetic limb components with respect to each other during the initial fitting or after the patient has worn the prosthetic limb for a period of time. The four-sided boss 12 engagement with the pyramid receptacle 40 allows the prosthetist to adjust the angular orientation before fixing it in place. However, the foregoing configuration requires several components and takes up considerable linear space. It is critically necessary to preserve the same pivoting axes on the prosthetic side, at the same height, as would have existed with the non-prosthetic limb. However, with certain transfemoral amputees, the allocable distance between the distal end of the patient's residual limb and the patient's natural knee center is very short, and it is difficult to size the foregoing plate member 16, and pyramid receptacle 40 so that the combined length of the components between a prosthetic limb socket 22 and the prosthetic knee joint 60 is equal to the distance between the distal end of the patients residual limb and the patient's natural knee center. If the combined length of the coupling components is too long the knee center on the prosthetic side will be too low, thus causing gait deviation.
The same issues arise for transtibial (below the knee) patients because the very same length requirements apply beneath the distal end of the residual limb and the prosthetic foot.
Accordingly, there is a need for a prosthetic-limb coupling-socket adapter assembly suitable for both transfemoral (above the knee) patients as well as transtibial (below the knee) patients, that affords rotatable (angular) adjustment for the prosthetic limb or foot, yet does not significantly increase the profile or length of the attachment of the interconnection components.